I joint PHD4ENERGY program in 2014 and my supervisor is Mats-Erik Pistol. I am using the Scattering matrix core function with Matlab to calculate nanowire array absorption. I intend to find the optimum geometry for multi-junction nanowire-based solar cells, where the Shockley-Queisser efficiency is maximised. This also involves finding the best materials in the different junctions and is a quite difficult problem due to the large number of parameters involved. In the future, I will work on nanowire LEDs to maximize the light emission in the forward direction. And I will also find out suitable alloy compositions in strained heterostructured core-shell LEDs for emission at the most used R, G, and B colors.